These kind of press rolls intended for forming a nip are well-known in the art. Prior art solutions include e.g. the structure disclosed in German Patent Specification No. 279,107. A drawback of this known device is its relatively complicated structure and that the roll width has to be great, because the rigid fastenings of an elestric shell at the ends of the rolls cause problems in use. Consequently, the roll has to be so broad that the different bending of the elastic shell at the ends of the roll does not cause problems. However, an increased roll width results in problems caused by bending, which requires an even more complicated structure.
The structure described in PCT Patent Application No. WO 82/02567 may be mentioned as another example of prior solutions. In this solution the body of the roll is unrotatable, and, in addition, provided with a backing block arranged at the press point. A rotating surface layer of an elastic material is provided around the roll body and the backing block. This surface layer of an elastic material is positioned close against the body, and lubrication is provided between the body and the surface layer. A drawback of this known solution is its complexity and the sealing problems caused by the lubricant and the pressure medium.
A third example of the prior art would be the solution disclosed in Finnish Patent Application No. 840,795. This structure, too, utilizes a stationary roll body in which a press shoe is arranged. An elastic press band rotatable with respect to the body is arranged around the body and the press shoe. Oil is applied between the band and the body in order to cool the press band and to lubricate the slide surface of the press shoe. This known solution has the same drawbacks as described above in connection with PCT Patent Application No. WO 82/02567.